Systems and methods for metal recovery

ABSTRACT

Various embodiments provide a process roasting a metal bearing material under oxidizing conditions to produce an oxidized metal bearing material, roasting the oxidized metal bearing material under reducing conditions to produce a roasted metal bearing material, and leaching the roasted metal bearing material in a basic medium to yield a pregnant leach solution.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a nonprovisional application of and claims priorityto U.S. Provisional Application Ser. No. 61/577,995, entitled “SYSTEMSAND METHODS FOR METAL RECOVERY” which was filed on Dec. 20, 2011. Theaforementioned application is hereby incorporated by reference herein inits entirety.

FIELD OF INVENTION

The present disclosure relates, generally, to systems and methods forrecovering metal values from metal bearing materials, and morespecifically, to systems and methods for processing acid consuming ores.

BACKGROUND OF THE INVENTION

Hydrometallurgical treatment of metal bearing materials, such as copperores, concentrates, and other metal bearing materials, has been wellestablished for many years. Typically, conventional hydrometallurgicalprocesses for copper recovery involve leaching metal bearing materialswith an acidic solution, either atmospherically or under conditions ofelevated temperature and pressure. The resultant process stream—thepregnant leach solution—is recovered, and a processing step such assolution extraction is used to form a highly concentrated and relativelypure metal value containing aqueous phase. One or more metal values maythen be electrowon from this aqueous phase.

Certain ores consume a relatively high amount of acid during acidicleaching. Thus, highly acid consuming ores have conventionally been moreexpensive to process through acidic leaching. Highly acid consumingcopper containing ores include copper carbonates, such as azurite andmalachite, among other types of minerals.

Certain ores and/or flotation tailings contain a mix of oxides andsulfides of one or more metals associated with highly acid consuminggangue materials such as carbonates. These mixed materials may beproblematic in acid leaching because of the highly acid consuming natureof the gangue minerals and because sulfide minerals leach more slowlyand less completely than oxide minerals, causing low metal recovery andplant design complications.

Accordingly, processes that allow for metal recovery from highly acidconsuming ores without the need for acid leaching would be advantageous.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides systems and methods formetal value recovery. In various embodiments, a process is providedcomprising roasting a metal bearing material under oxidizing conditionsto produce an oxidized metal bearing material, roasting the oxidizedmetal bearing material under reducing conditions to produce a reducedmetal bearing material, and leaching the roasted metal bearing materialin a basic medium to yield a pregnant leach solution. In variousembodiments, the pregnant leach solution is subjected to solutionextraction.

Further, various embodiments of the present invention provide a processcomprising one or more of oxidizing sulfides of copper and cobalt byroasting under an oxygen containing gas to produce an oxidized copperand cobalt bearing material, reducing copper and cobalt by roasting theoxidized copper bearing material under a reducing gas which may comprisehydrogen, carbon monoxide, another reducing gas such as those describedherein, and/or mixtures thereof, to produce a roasted copper and cobaltbearing material, leaching the roasted copper and cobalt bearingmaterial using free ammonia and an ammonium complex to yield a pregnantleach solution, recovering copper by solvent extraction andprecipitating cobalt containing compounds from the solvent extractionraffinate solution, and electrowinning the copper.

Still in further exemplary embodiments, a system is provided comprisingan oxidizing roaster configured to receive oxygen gas and configured toheat a metal bearing material to temperatures of from about 200° C. toabout 800° C., a reducing roaster configured to receive at least one ofcarbon monoxide gas and hydrogen gas and configured to heat the metalbearing material to temperatures of from about 200° C. to about 800° C.,a quench vessel configured to receive a roasted metal bearing materialfrom the roaster, a basic leaching vessel or vessels in seriesconfigured to receive quenched metal bearing material from the quenchvessel, one or more solvent extraction stages configured to receive ahigh pH solution containing copper and cobalt, one or more wash stagesconfigured to receive loaded organic from the solvent extraction stage,one or more stripping stages configured to receive washed loaded organicfrom the wash stage, a copper electrowinning circuit configured toreceive rich electrolyte solution from the stripping stage, and a cobaltprecipitation vessel configured to receive raffinate from the solventextraction stage.

Further areas of applicability will become apparent from the detaileddescription provided herein, it should be understood that thedescription and specific examples are intended for purposes ofillustration only and are not intended to limit the scope of the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter of the present invention is particularly pointed outand distinctly claimed in the concluding portion of the specification. Amore complete understanding of the present invention, however, may bestbe obtained by referring to the detailed description and claims whenconsidered in connection with the drawing figures, wherein like numeralsdenote like elements and wherein:

FIG. 1 is a flow diagram illustrating a process that does not include anacid leach, in accordance with various embodiments of the presentinvention; and

FIG. 2 is a flow diagram illustrating a further process that does notinclude an acid leach, in accordance with various embodiments of thepresent invention.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present invention, its applications, or its uses.It should be understood that throughout the drawings, correspondingreference numerals indicate like or corresponding parts and features.The description of specific examples indicated in various embodiments ofthe present invention are intended for purposes of illustration only andare not intended to limit the scope of the invention disclosed herein.Moreover, recitation of multiple embodiments having stated features isnot intended to exclude other embodiments having additional features orother embodiments incorporating different combinations of the statedfeatures.

Furthermore, the detailed description of various embodiments hereinmakes reference to the accompanying drawing figures, which show variousembodiments by way of illustration. While the embodiments are describedin sufficient detail to enable those skilled in the art to practice theinvention, it should be understood that other embodiments may berealized and that logical and mechanical changes may be made withoutdeparting from the spirit and scope of the present invention. Thus, thedetailed description herein is presented for purposes of illustrationonly and not of limitation. For example, steps or functions recited indescriptions any method, system, or process, may be executed in anyorder and are not limited to the order presented. Moreover, any of thestep or functions thereof may be outsourced to or performed by one ormore third parties. Furthermore, any reference to singular includesplural embodiments, and any reference to more than one component mayinclude a singular embodiment.

The present invention relates, generally, to systems and methods forrecovering metal values from metal-bearing materials, and morespecifically, to systems and methods for metal recovery using basicleaching. These improved systems and methods disclosed herein achieve anadvancement in the art by providing a metal value recovery system thattends to avoid the use of acid leach media with high acid consumingmetal-bearing materials. Such technology tends to reduce the cost ofmetal recovery by, at least, reducing the amount of acid needed to leacha given ore body mass.

In particular, it has been discovered that one or more roasts may becombined with a basic leach to leach metal values from metal bearingmaterials such as ore. In that regard, in various embodiments, one ormore roasts may be combined with a leach in basic media to yield a metalvalue containing material that is suitable for use in a conditioningprocess, such as solution extraction.

With reference to FIG. 1, metal recovery 100, in accordance with variousembodiments, is illustrated. Metal recovery 100 allows for metal valuesto be recovered from a basic leach without an acid leach. Metal recovery100 includes ore 102, which contains one or more metal values.

Ore 102 may comprise any metal hearing material, such as an ore, acombination of ores, a concentrate, a process residue, a flotationtailings product, an impure metal salt, combinations thereof, or anyother material from which metal values may be recovered. Metal valuessuch as, for example, copper, gold, silver, zinc, platinum group metals,nickel, cobalt, molybdenum, rhenium, uranium, rare earth metals, and thelike may be recovered from ore 102 in accordance with variousembodiments of the present invention. Various aspects and embodiments ofthe present invention, however, prove especially advantageous inconnection with the recovery of copper from highly acid consuming oresthat include copper carbonates, such as azurite and malachite, amongother highly acid consuming ores and gangue minerals. Highly acidconsuming ores may comprise any metal bearing material that requires ahigh ratio of acid to metal bearing material volume to leach acommercially significant proportion of the metal values in the metalbearing material. In various embodiments, ore 102 comprises at leastcopper and cobalt and/or compounds comprised of copper and/or cobalt.

Ore 102 may be prepared in preparation 104. Preparation 104 may includeany form of preparation for ore 102 prior to roasting 106. In variousembodiments, preparation 104 is omitted, although various advantages maybe derived through the use of preparation 104. Metal bearing materialsmay be prepared in a variety of ways. Ores may be dried, crushed,pulverized, finely ground, or undergo any combination thereof. Ores maybe concentrated to form a metal bearing concentrate. A variety ofacceptable techniques and devices for reducing the particle size of theore 102 are currently available, such as crushers, ball mills, towermills, ultrafine grinding mills, attrition mills, stirred mills,horizontal mills and the like, and additional techniques may later bedeveloped that may achieve the desired result of increasing the surfacearea of and exposing mineral surfaces within the material to beprocessed. In accordance with various embodiments, ore 102 may beprepared in preparation 104 by controlled, grinding. For example, auniform, particle size distribution may be achieved. In accordance withone aspect of the present disclosure, a particle size distribution ofapproximately 80% particle distribution passing size (P₈₀) of about 75microns may be used, as well as a particle size distribution ofapproximately 98% particle distribution passing size (P₉₈) of about 100to about 200 microns. In accordance with one aspect of the presentdisclosure, a particle size distribution of approximately 80% particledistribution passing size (P₈₀) of about 74 microns may be used.

However, in various embodiments, a uniform, ultra-fine particle sizedistribution is not necessary. For example, in various embodiments, aparticle size distribution of approximately 80% particle distributionpassing size (P₈₀) of about 100 microns may be used, and in variousembodiments a particle size distribution of approximately 98% particledistribution passing size (P₉₈) of about 100 microns may be used. Invarious embodiments, preparation 104 does not include controlledgrinding, but does include crushing and grinding to produce largerand/or less uniform particle sizes. For example, preparation 104 maycomprise screening ore through a grizzly or other analogous device withabout 250 mm openings. Further, preparation 104 may also include a milloperation. Particles having a size of less than about 250 mm can bereceived by mill operation which then reduces the received particles toa particle size distribution suitable for downstream processing. Forexample, the mill operation may provide particles having about 80%particle distribution passing size (P₈₀) of 100 microns. Other particlesizes described herein may also be useful. Preparation 104 yields aprepared ore that may be subject to oxidizing roast 106.

Oxidizing roast 106 comprises a roast performed under oxidizingconditions and may be performed using one or more oxidizing agents. Forexample, oxidizing roast 106 may be performed using oxidizing agent 122.Oxidizing agent may comprise air, oxygen gas (O₂), ozone (O₃), or acombination thereof. During oxidizing roast 106, oxidizing agent 122 maybe injected or otherwise introduced into a roasting vessel. Oxidizingagent 122 may be introduced into oxidizing roast 106 until a suitableconcentration of oxidizing agent 122 is achieved in the roasting vessel.

The temperature of the roasting vessel during oxidizing roast 106 may beadjusted to any suitable roasting temperature. For example, oxidizingroast 106 may be performed at from about 500° C. to about 750° C., morepreferably from about 550° C. to about 700° C., and still morepreferably at about 625° C. to about 675° C. In various embodiments,oxidizing roast 106 is performed at about 650° C. Oxidizing roast 106produces oxidized metal bearing material.

Reducing roast 108 comprises a roast performed under reducing conditionsand may be performed using one or more reducing agents. For example,reducing roast 108 may be performed using reducing agent 120. Reducingagent 120 may comprise carbon monoxide gas (CO), hydrogen gas (H₂),other suitable reagent, or combinations thereof. During reducing roast108, carbon monoxide gas and/or hydrogen gas may be injected orotherwise introduced into a roasting vessel. The carbon monoxide gas orhydrogen gas may be introduced into reducing roast 108 until a suitableconcentration of carbon monoxide gas or hydrogen gas is achieved in theroasting vessel. Carbon monoxide gas and/or hydrogen gas may beintroduced into the roaster as preferably at least 90% carbon monoxidegas and/or hydrogen gas, preferably at least 95% carbon monoxide gasand/or hydrogen gas, and more preferably, about 100% carbon monoxide gasand/or hydrogen gas. The amount of reducing agent used is preferably atleast the amount needed to reduce metal values that may be laterrecovered (e.g, copper and cobalt) to their elemental metallic form plusan excess portion to assure that the reduction reactions can reachsubstantial completion. During reducing roast 108, carbon monoxide gas,hydrogen gas, carbon containing solids, and mixtures thereof may beinjected or otherwise introduced into a roasting vessel. The carbonmonoxide gas or hydrogen gas may be introduced into reducing roast 108until a suitable concentration of carbon monoxide gas or hydrogen gas isachieved in the roasting vessel.

In various embodiments, hydrogen gas is used as a reducing agent. Theprincipal reaction product of the reducing reaction in the gas phasewould be water. Thus, in such embodiments, water may be condensed fromthe exhaust gas into a liquid phase. The exhaust gas, which may containhydrogen gas, may then be recycled into the roaster.

Carbon monoxide may be obtained from any suitable source. For example,carbon monoxide may be obtained from the burning of coke. Hydrogen gasmay be obtained from any suitable source. For example, hydrogen gas maybe produced by fossil fuel reforming. Fossil fuel reforming may comprisereacting steam and a fuel source to produce hydrogen. For example,diesel fuel, natural gas (methane), propane, and gasoline may be used asa fuel for fossil fuel reforming. In addition, fossil fuel reforming maynot require a “fossil” fuel per se but a fuel that may be similar to afossil fuel. For example, in certain circumstances, oils of plants oranimals and/or ethanol may be used in addition to or in place of fossilfuels.

The temperature of the roasting vessel during reducing roast 108 may beadjusted to any suitable roasting temperature. For example, reducingroast 108 may be performed at about 400° C. to 625° C., more preferablyabout 475° C. to about 575° C., and still more preferably at about 500°C. to about 550° C. In various embodiments, reducing roast 108 isperformed at about 540° C. Reducing roast 108 produces reduced metalbearing material.

The temperature of the roasting vessel during reducing roast 108 may beadjusted to any suitable roasting temperature. For example, reducingroast 108 may be performed at about 400° C. to 625° C., more preferablyabout 475° C. to about 575° C., and still more preferably at about 500°C. to about 550° C. In various embodiments, reducing roast 108 isperformed at about 540° C.

Reducing roast 108 and oxidizing roast 106 may take place in two stageroaster. A two stage roaster may comprise one chamber configured toperform reducing roast 108 and an additional chamber configured toperform oxidizing roast 106. In various embodiments, reducing roast 108and oxidizing roast 106 may take place in separate roasters.

After roasting (whether oxidative, reductive, or both), metal hearingmaterial may be quenched or otherwise treated prior to subsequentprocessing. Quenching, for example, may be used to reduce thetemperature of roasted metal bearing material after a roast iscompleted. Quenching provides a transition from the elevatedtemperatures of roasting to a temperature closer or equal to that ofambient temperature. In the case in which the ore has been reduced inthe roasting step, quenching may also serve to limit the re-oxidation ofthe reduced material. Quench media may be water or a basic solutionwhich may contain free ammonia and an ammonia compound.

After reducing roast 108, reduced metal bearing material may be subjectto ammonia/ammonium leach 110. In accordance with various aspects,ammonia/ammonium leach 110 comprises an agitated tank leach.Ammonia/ammonium leach 110 may comprise an agitated tank leach that isperformed at constant or varying basic pH levels. Basic pH levels mayrange from about 7 to about 14. Ammonia/ammonium leach 110 is performedusing basic media containing ammonia or ammonium compounds. For example,the basic media used in ammonia/ammonium leach 110 basic media mayinclude an aqueous solution of ammonia, ammonium and/or ammoniumcontaining compounds such as ammonium carbonate, ammonium sulfate andcombinations thereof. One or more metal values from the reduced metalbearing material may be absorbed into the basic media. Basic media thatcontains metal values may be referred to as a pregnant leach solution.Leach solutions may contain recycled solutions from upstream processesand recovered lixiviant from various processing steps. Fresh lixiviantmay also be added. Leaching may occur in several tanks, eitherco-currently or counter-currently depending on the leach characteristicsand kinetics. Preferably, the duration of leaching in accordance withvarious aspects of the present invention ranges from about 2 hours toabout 8 hours. More preferably, the duration ranges from about 4 hoursto about 7 hours.

The pregnant leach solution may be present with solids inammonia/ammonium leach 110. Together, the pregnant leach solution andsolids of ammonia/ammonium leach 110 may be referred to as a slurry.

The slurry from ammonia/ammonium leach 110 is subject to solid liquidphase separation 112. Solid liquid phase separation 112 may comprise anyof the solid liquid phase separation techniques described herein orhereinafter developed. Liquids from solid liquid phase separation 112may be forwarded to SX 114.

SX 114 may comprise any solution extraction process. In variousembodiments, SX 114 comprises a liquid-liquid extraction. During SX 114,metal values from the liquids from solid liquid phase may be loadedselectively into an organic phase in an extraction phase, wherein theorganic phase comprises an extracting agent to aid in transporting themetal values to the organic phase. The extraction phase may produce anaqueous raffinate. The organic phase from the extraction stage may bethen subjected to a solvent stripping phase, wherein the metal valuesare transferred to an aqueous phase. For example, more acidic conditionsmay shift the equilibrium conditions to cause the metal values tomigrate to the aqueous phase. Metal value containing liquid from SX 114may be referred to as a loaded aqueous stream.

The loaded aqueous stream from SX 114 may be subject to furtherprocessing, such as electrowinning, to yield a metal value.

In electrowinning, in accordance with various embodiments, the anode isconfigured to enable the electrolyte to flow through it. As used herein,the term “flow-through anode” refers to an anode so configured.

Any now known or hereafter devised flow-through anode may be utilized inaccordance with various aspects of the present invention. Possibleconfigurations include, but are not limited to, metal wool or fabric, anexpanded porous metal structure, metal mesh, multiple metal strips,multiple metal wires or rods, perforated metal sheets, and the like, orcombinations thereof. Moreover, suitable anode configurations are notlimited to planar configurations, but may include any suitablemultiplanar geometric configuration.

While, in various embodiments, anodes may be lead-containing (e.g.,Pb—Sn—Ca), preferably, the anode is formed of one of the so-called“valve” metals, including titanium (Ti), tantalum (Ta), zirconium (Zr),or niobium (Nb). The anode may also be formed of other metals, such asnickel, or a metal alloy, intermetallic mixture, or a ceramic or cermetcontaining one or more valve metals. For example, titanium may bealloyed with nickel (Ni), cobalt (Co), iron (Fe), manganese (Mn), orcopper (Cu) to form a suitable anode. Preferably, the anode comprisestitanium, because, among other things, titanium is rugged andcorrosion-resistant. Titanium anodes, for example, when used inaccordance with various aspects of embodiments of the present invention,potentially have useful lives of up to fifteen years or more. Titaniumanodes may comprise titanium-clad anodes. Titanium-clad anodes comprisea metal, such as copper, clad in titanium,

The anode may also comprise any electrochemically active coating.Exemplary coatings include those that comprise platinum, ruthenium,tantalum, iridium, other Group VIII metals, oxides of the same, andmixtures of the same. Ruthenium oxide, tantalum oxide, and iridium oxideare preferred for use as the electrochemically active coating ontitanium anodes when such anodes are employed in connection with variousembodiments. In accordance with one embodiment of the invention, theanode is formed of a titanium metal mesh coated with an iridium oxideand/or tantalum oxide-based coating. In such embodiments, the iridiumoxide and/or tantalum oxide-based coating may be comprised of multiplelayers of iridium oxide and/or tantalum oxide. The multiple layers maycomprise iridium oxide and/or tantalum oxide in an amorphous state or acrystalline state. In another embodiment of the invention, the anode isformed of a titanium mesh coated with a ruthenium-based oxide coating.Anodes suitable for use in accordance with various embodiments of theinvention are available from a variety of suppliers.

In various embodiments, copper electrowinning operations use either acopper starter sheet or a stainless steel or titanium “blank” as thecathode. In accordance with one aspect of an exemplary embodiment, thecathode is configured as a metal sheet. The cathode may be thrilled ofcopper, copper alloy, stainless steel, titanium, or another metal orcombination of metals and/or other materials. The cathode is typicallysuspended from the top of the electrochemical cell such that a portionof the cathode is immersed in the electrolyte within the cell and aportion (generally a relatively small portion, less than about twentypercent (20%) of the total surface area of the cathode) remains outsidethe electrolyte bath. The total surface area of the portion of thecathode that is immersed in the electrolyte during operation of theelectrochemical cell is referred to herein, and generally in theliterature, as the “active” surface area of the cathode. This is theportion of the cathode onto which copper is plated duringelectrowinning.

In accordance with various embodiments of the present invention, thecathode may be configured in any manner now known or hereafter devisedby the skilled artisan.

In accordance with various embodiments, the copper concentration in theelectrolyte for electrowinning is advantageously maintained at a levelof from about 20 to about 60 grams of copper per liter of electrolyte.Preferably, the copper concentration is maintained at a level of fromabout 30 to about 50 g/L, and more preferably, from about 40 to about 45g/L. However, various aspects of the present invention may bebeneficially applied to processes employing copper concentrations aboveand/or below these levels.

With reference to FIG. 2, copper recovery process 200 is illustrated.Ore 202 may comprise any copper bearing ore. Ore 202 may be subject todry grinding 204, in accordance with any of the grinding processesdescribed herein. For example, dry grinding 204 may comprise grindingthe ore to a P80 of 60 to 100 microns, preferably about 75 microns. Drygrinding 204 yields ground ore, which may be subject to oxidationroasting 206.

Oxidation roasting 206 may comprise any of the oxidative roastsdescribed herein. For example, oxidation roasting 206 may compriseheating ground ore at about 625° C. to about 675° C. under an oxidizingagent. Oxidation roasting may take place in a fluidized bed roaster. Theoxidation process may take between about 10 and about 30 minutes,preferably about 20 minutes. Oxygen (O₂) gas may be used an oxidizingagent. Oxygen gas is produced at oxygen plant 210 using any knowntechnique. For example, oxygen may be distilled from ambient air. Offgas 208 is configured to release gas from oxidation roasting 206.Oxidation roasting 206 may yield oxidized ore, which may be subject toreduction roasting 214.

Reduction roasting 214 may comprise any of the reductive roastsdescribed herein. For example, reduction roasting 214 may compriseheating ground ore at about 500° C. to about 550° C. under a reducingagent. Reducing gasses are introduced into a fluidized bed roaster.Retention time in the roaster may be from about 10 to about 30 minutes,preferably about 20 minutes. Hydrogen (H₂) gas 216 may be used areducing agent. Hydrogen gas may be produced by hydrogen plant 222.Hydrogen plant 222 may use diesel fuel or another suitable hydrocarbon218 and steam 221 in a steam reforming process 224 to produce hydrogengas 216. Reduction roasting 214 yields reduced ore. Reduced ore maybesubject to calcine cooling 232 to cool the reduced ore. The reduced oremay then be subject to ammonia/ammonium carbonate leach 234.

Hydrogen plant 222 exhausts carbon dioxide 226. Carbon dioxide 226 maybe advantageously recycled and combined with ammonia to form ammoniumcarbonate 230.

Ammonia/ammonium carbonate leach 234 may comprise a leaching processusing basic media comprising ammonia and/or ammonium carbonate. Ammonia220 may be combined with ammonium carbonate 230 for use in the basicmedia of ammonia/ammonium carbonate leach 234. Copper and cobaltcontained in the reduced ore may be leached into the basic media ofammonia/ammonium carbonate leach 234. The leach may comprise one or morestages arranged in either a co-current or a countercurrent processarrangement. Ammonia/ammonium carbonate leach 234 may output a pregnantslurry that is forwarded to CCD circuit 236. CCD circuit 236 is acounter current decantation circuit. CCD circuit 236 has 8 stages,though any suitable number of stages is contemplated herein. CCD circuit236 performs a solid liquid phase separation on the pregnant slurry. Theliquid phase from CCD circuit 236 may be referred to as pregnant leachsolution.

Pregnant leach solution from CCD circuit 236 may be subject to coppersolution extraction 238. Copper solution extraction 238 may comprise anysolution extraction process. In various embodiments, copper solutionextraction 238 comprises a liquid-liquid extraction. During coppersolution extraction 238, copper (e.g., ionic copper) from the liquidsfrom solid liquid phase may be loaded selectively into an organic phasein an extraction stage, wherein the organic phase comprises anextracting agent (e.g. a ketoxime, a modified ketoxime or analdoxime/ketoxime blend) to aid in transporting the copper to theorganic phase. The raffinate from the extraction stage may containsecondary metal values (e.g., cobalt). The raffinate may be subject tocobalt precipitation 242 to precipitate the cobalt from the raffinate.Cobalt may be recovered as cobalt sulfide or another relatively waterinsoluble form in CoS Product 244. The cobalt in the solid phase may berecovered using, for example, another leaching process.

The organic phase from the extraction stage of copper solutionextraction 238 may be then subjected to one or more wash stages in whichthe loaded organic phase is contacted with an aqueous phase in order toremove entrained ammonia bearing droplets from the organic phase. Thewashed organic phase may then be subject to a solvent stripping stage,wherein the copper is transferred to an aqueous phase. For example, moreacidic conditions may shift the equilibrium conditions to cause thecopper to migrate to the aqueous phase. Copper containing liquid fromcopper solution extraction 238 may be referred to as a loaded aqueousstream.

The loaded aqueous stream may be subject to copper electrowinning 240.Copper electrowinning 240 may comprise any process by which coppercathode product 246 is electrowon from the loaded aqueous stream. Invarious embodiments, copper electrowinning 240 may comprise producingcopper powder using a flow through cathode. Copper electrowinning 240may take place in one or more electrochemical cells. An electrochemicalcell generally comprises a cell, at least one anode, at least onecathode, and, in various embodiments, an electrolyte flow manifold.

It is believed that the disclosure set forth above encompasses at leastone distinct invention with independent utility. While the invention hasbeen disclosed in the exemplary forms, the specific embodiments thereofas disclosed and illustrated herein are not to be considered in alimiting sense as numerous variations are possible. Equivalent changes,modifications and variations of various embodiments, materials,compositions and methods may be made within the scope of the presentinvention, with substantially similar results. The subject matter of theinventions includes all novel and non-obvious combinations andsubcombinations of the various elements, features, functions and/orproperties disclosed herein.

Benefits, other advantages, and solutions to problems have beendescribed herein with regard to specific embodiments. However, thebenefits, advantages, solutions to problems, and any element orcombination of elements that may cause any benefit, advantage, orsolution to occur or become more pronounced are not to be construed ascritical, required, or essential features or elements of any or all theclaims of the invention. Many changes and modifications within the scopeof the instant invention may be made without departing from the spiritthereof, and the invention includes all such modifications.Corresponding structures, materials, acts, and equivalents of allelements in the claims below are intended to include any structure,material, or acts for performing the functions in combination with otherclaim elements as specifically claimed. The scope of the inventionshould be determined by the appended claims and their legal equivalents,rather than by the examples given above.

The invention claimed is:
 1. A process comprising: roasting a metalbearing material comprising a copper carbonate under oxidizingconditions to produce an oxidized metal bearing material; roasting theoxidized metal bearing material under reducing conditions, at atemperature of about 475° C. or greater, to produce a roasted metalbearing material; and leaching the roasted metal bearing material in abasic medium to yield a pregnant leach solution.
 2. The process of claim1, wherein the basic medium comprises at least one of ammonia, ammoniumcarbonate and ammonium sulfate.
 3. The process of claim 1, wherein theoxidizing conditions comprise an oxygen gas containing atmosphere. 4.The process of claim 1, wherein the reducing conditions comprise ahydrogen gas containing atmosphere.
 5. The process of claim 1, furthercomprising subjecting the pregnant leach solution to a solutionextraction process to yield a loaded aqueous stream.
 6. The process ofclaim 5, wherein an extraction stage of the solution extraction yields acobalt-bearing raffinate.
 7. The process of claim 6, further comprisingprecipitating cobalt from the cobalt-bearing raffinate.
 8. The processof claim 7, wherein the precipitating yields cobalt sulfide in a solidphase.
 9. The process of claim 8, wherein the cobalt sulfide issubjected to leaching.
 10. The process of claim 5, subjecting the loadedaqueous stream to electrowinning.
 11. The process of claim 1, whereinthe copper carbonate comprises at least one of azurite and malachite.